Iran, which on Monday executed 10 accused drug traffickers, is maintaining its record-setting use of capital punishment, a UN investigator said.
Ahmad Shaheed, a former foreign minister for the Maldives, said ahead of the presentation of his latest report that conditions were worsening in Iran on the use of the law and discrimination against religious and ethnic minorities, women and gays.
"Allegations contained in this report paint a disturbing picture of a government that seriously struggles to comply with its international and national obligations," Shaheed told a meeting with diplomats, journalists and experts.
"The concerns remain unabated -- if anything, they are growing," he said of Iran's use of executions and accusations of persecution and discrimination.
Shaheed said more than 300 people had been recorded executed in the first eight months of the year but the figure was probably much higher as Iran has restricted information this year.
He reported 670 executions in 2011 in Iran, which has the world's highest per capita use of the death penalty.
"I don't see it as reducing," said the UN special rapporteur on human rights in Iran, who will present his latest report to a UN General Assembly committee on Wednesday.
Shaheed said he had been "shocked" to hear of the execution of 10 men in a Tehran jail after they had been found guilty of trafficking narcotics.
"It is quite commonplace to have large numbers of people executed on the same day in Iran," said Shaheed, who has not been able to visit the country since taking up his post in June 2011.
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Iran has drawn up a new penal code, still being considered by parliament, which Shaheed said "omits" the use of stoning for executions.
But he added that this does not stop a judge ordering the controversial execution. "Under the constitution of Iran, where the law is silent, a judge has to refer to the Sharia" -- the Islamic law which still allows stoning.
The expert said the new penal code also allows a provision to avoid death sentences for juvenile offenders.
Iran has been strongly condemned by rights groups for the widespread executions of those under the age of 18. Shaheed said Iran was still out of line with international conventions which bar the execution of minors.
Shaheed's report says that human rights activists in Iran are beaten with batons and threatened with mock hangings, rape, sleep deprivation, and threats that relatives will be raped or killed.
He added that more than 40 journalists were also known to be detained, making the country one of the worst press freedom offenders.
"Rule of law issues are some of the major concerns I have with Iran," Shaheed said, highlighting vague charges, unfair trials and sentencing. The report also criticizes Iran over discrimination against women and religious and ethnic minorities.
But Shaheed said he would be looking into the human rights impact of international sanctions against Iran over its nuclear program.
A government newspaper said Sunday that six million patients had been affected as medicines were difficult to get hold of. Medicines are not covered by the UN sanctions ordered against Iran's uranium enrichment.
The investigator said there were "concerns" about the impact of sanctions and that he hoped to visit the country to make a study.
Shaheed's report is 23 pages long, while Iran's comments run to 66 pages. It has called his allegations "baseless" and his investigation "illegitimate" and politicized.